Citrix Systems 9.2 Benutzerhandbuch

The following two operators encode and decode a text string by applying the 
Base64 encoding algorithm:

The EXTEND operator is used in rewrite actions that specify patterns or pattern 
sets and target the bodies of HTTP packets. When a pattern match is found, the 
EXTEND operator extends the scope of the search by a predefined number of 
bytes on both sides of the matching string. A regular expression can then be used 
to perform a rewrite on matches in this extended region. Rewrite actions that are 
configured with the EXTEND operator perform rewrites faster than rewrite 
actions that evaluate entire HTTP bodies using only regular expressions.

The format of the EXTEND operator is EXTEND(m,n), where m and n are the 
number of bytes by which the scope of the search is extended before and after the 
matching pattern, respectively. When a match is found, the new search scope 
comprises m bytes that immediately precede the matching string, the string itself, 
and the n bytes that follow the string. A regular expression can then be used to 
perform a rewrite on a portion of this new string.

The EXTEND operator can be used only if the rewrite action in which it is used 
fulfills the following requirements:

•

The search is performed by using patterns or patterns sets (not regular 
expressions) 

•

The rewrite action evaluates only the bodies of HTTP packets. 

Additionally, the EXTEND operator can be used only with the following types of 
rewrite actions:

•

replace_all

•

insert_after_all

text.B64ENCODE

Encodes the text string (designated by text) by applying the 
Base64 encoding algorithm.

text.B64DECODE

Decodes the Base64-encoded string (designated by text) by 
applying the Base64 decoding algorithm. The operation 
raises an UNDEF if text is not in B64-encoded format.